The field of prosthetics, in general, has made great advancements in improving performance on multiple levels for amputees and congenitally deformed individuals. Through these advancements, people across the world are experiencing new aspects of life and reaching new heights of applicability never before thought possible.
Most prosthetic systems, also called prostheses, have a socket that directly interfaces with the prosthesis and a residual limb of the wearer. For purposes of clarity herein, the term “suspension” refers to how the socket and residual limb are coupled to one another. Generally, a firmer suspension increases the effectiveness and efficiency of the interaction of the prosthesis and residual limb. Some common methods of suspension include a suspension sleeve, a locking pin mechanism, a corset, or a suspension belt. However, each of these systems may still have various limitations in versatility and performance.
One relatively successful suspension method incorporates a pump system that utilizes a suspension sleeve to create an air seal between the prosthesis and the residual limb. A small mechanical pump activated during the wearer's normal gait cycle generates a vacuum pressure of up to about fifteen inches of Mercury (50,795 Pascal) on the residual limb. Such a pump system has been found to have superior benefits compared to other, non-vacuum type systems. By way of example, pump systems have been found to promote improved health of the residual limb by increasing circulation.
Further, pump systems may promote a better “fit” of the prosthesis relative to the residual limb. The “fit” of the prosthesis is one of the major issues that must be dealt with whether in the design of the prosthesis, its control logic, its calibration methods, by the interface between the prosthesis and the limb (e.g., liner or gel sock), or any combination thereof. The fit is dependent on volumetric changes of the residual limb, which may be caused by temperature, fluid flow, local stress on portions of the limb, and possibly many other factors. As a result of the residual limb changing in size the prosthesis may slip or undesirably move relative to the limb. Incorporation of a vacuum pump may help reduce or eliminate undesired size changes of the residual limb. Thus, the vacuum pump may allow a better fit of the prosthesis by maintaining an appropriate pressure on the residual limb throughout daily use.
However, pump systems do have some limitations as compared to more conventional, non-vacuum type systems. For example, pump systems may have a less appealing cosmetic or aesthetic appearance, they may be less versatile, they may have a higher mass, and higher audible or inaudible noise levels. In addition, control systems used in conjunction with the pump systems may not adequately replicate or respond to natural human locomotion due to dynamic loading, impact or shock loading, or complex load cycles that may be generated by active individuals.
One conventional prosthesis and method of controlling the prosthesis are described in U.S. Pat. No. 5,724,714. The prosthesis includes an inflatable bladder within the socket. The fit of the prosthesis is controlled by pumping air to or from the bladder in an attempt to improve or maintain a desired fit. While this approach may provide a comfortable fit, it incorporates a dual-socketed system that is spatially bulky and heavy. The inflatable bladder focuses on pre-determined weight-bearing regions of the residual limb, but over time these “pressure points” may lead to residual limb swelling or other undesired changes. Furthermore, this method does not prevent limb volumetric changes, but rather attempts to dynamically react to those changes after they have occurred.
U.S. Pat. Nos. 5,549,709 and 6,231,616 describe pump systems that respectively cooperate with a multi-socketed system. These devices, however, do not incorporate any software control of the pump system and do not have intelligent manipulation of the socket environment. Additionally, they do not incorporate a means of recording environmental changes or use of the prosthesis, amongst others.
U.S. Pat. No. 6,926,742 describes a mechanism for detecting and correcting a drop in pressure in a socket of a prosthesis, but the mechanism may be undesirably noisy when one or more pumps or motors of the prosthesis are turned on.
The eVAC® vacuum type prosthesis, developed by Smith Global, aims to promote a vacuum in the space that is formed between a gel liner and a prosthetic socket by electronic means. The eVAC® prosthesis does not have a mechanism for recording wearer data and does not have intelligent control of the socket environment; instead it is only adjustable with preset settings. Other vacuum type prostheses include the Harmony® VASS™ (Vacuum-Assisted Pump system) developed by TEC Interface Systems and the LimbLogic™ VS remote-controlled vacuum suspension system developed by The Ohio Willow Wood Company.